Automatic volume control



Feb., 17, 1942. Q o, NELSON 2,273,760

AUTOMATIC VOLUME CONTROL Original Filed Oct. 28. 1938 ATTORNEYS Patented Feb. 17, 1942 AUTGMATC VLUME CGNIROL Curtis 0. Nelson, Beileviile, 11.1.

ctober 28, 1938, Serial No. No. 2,197,312, dated April 16, 1946. Divided and this application August 28, 1939, Serial No. 292,329

Original application O 237,583, now Patent 1 Claim.

My invention relates to radio receivers and has among its objects and advantages the provision of an automatic volume control.

The present case is a divisional application based on my parent application, Serial No. 237,563, filed October 28, 1938, on Automatic broadcasting station selector and volume control, now matured into Patent 2,197,312, issued April 16, 1940.

An object of my invention is to provide novel volume control which operates to maintain the volume of sound from the receiving set substantially uniform and which is automatically actuated as an incident to adjustment of the condenser to predetermined stations to be tuned in. While atmospheric conditions, distance and the like may weaken or strengthen signals, the volume control embodies means whereby precise adjustment may be manually secured for correcting deficiencies in the automatic adjustment.

In the accompanying drawing:

Figure l is a plan view of the automatic volume control;

Figure 2 is a side elevation View of the structure of Figure 1; and

Figure 3 is a sectional View taken substantially along the line 3-3 of Figure 2.

In the embodiment selected to illustrate my invention, I make use oi la bracket 3l6 having a threaded shank 318 extending through the opening 326 in the wall or panel 32|. A nut 322 clamps the bracket to the Wall. Bracket 3I6 carries a bar 324, an upright post 326 formed integrally with the bar and a second bar 328 parallelling the bar 324. Post 326 interconnects the bar 324 and 328 at one end, while a cross piece or post 336 interconnects the opposite ends through the medium of screws 332. Bars 324 and 328 are grooved at 334 for slidably receiving a rack 336 arranged in mesh with a pinion 338 fixed to a shaft 346. Bars 324 and 328 are provided with openings 342 for rotatably sup porting the shaft 346, while the shank 318 is provided with an opening 344 loosely receiving the shaft. A knob 346 is fixed to the shaft 346 to permit manual rotation thereof.

Upon the rack 336, I mount a resistor 343, which resistor is insulated from the rack through the medium of a suitable strip 356 anchored to the elevations 352 on the rack 336 through the medium of screws 353.

Post 336 is provided with an opening 354 for slidably receiving a shaft 356 having a square reach 358 slidable in the square opening 366 in the post 326. A collar 362 is adjustably connected with the shaft 356 through the medium of a screw 364. Between the post 336 and the collar 362 and upon the shaft 356, I interpose a compression spring 366. The wire 368 of the volume control of the receiver is electrically connected with the post 336. Post 336 is in conducting relation with the shaft 356, while the collar 362 is also in conducting relation with the shaft. A feeler wire or wiper contact 316 is connected with the collar 362 at one end and has its other end contacting the resistor 348 and arranged to slide therealong. The other wire 312 of the volume control circuit is connected with one end of the resistor 348. The other end of the resistor is dead.

The outer end of the squared reach 353 is slotted at 314 to receive a wheel 316 rotatably mounted on a pin 318. Wheel 316 has pressure relation with the periphery of a volume cam 386 xedly connected with a rotatable condenser adjusting shaft 38|. Spring 366 urges the shaft 356 in the direction of the volume cam 386. Volume cam 386 is provided with peripheral recesses 382, 384, 386 and 388. Movement of the wiper contact 316 along the resistor 348 in the direction of the end to which the Wire 312 is connected provides a greater power output. The recesses 382 through 388 are spaced circumferentially about the volume cam 386 to represent different sending stations, the spacing being such as to selectively receive the roller 316 when the condenser of the receiving set is precisely positioned with respect to the sending station represented by the recess in which the roller 316 is at rest. The depths of the respective recesses are such as to vary the power output in accordance with the particular sending station to which the condenser of the receiver is tuned.

Frequently atmospheric conditions, distance and the like may weaken or strengthen signals. I provide means whereby the automatic volume control may be precisely adjusted. Rack 336 may be shifted longitudinally through the medium of the gear 338 manually actuated through the medium of the knob 346. Such adjustment of the rack 336 moves the resistor 348 relatively to the feeler wire 316. Adjustment of the resistor through the manual control increases or decreases the ratios of the recesses 382 to 388 in corresponding amounts. It will thus be seen that the manual control incorporated in the automatic volume control permits refinement to be made in the power output of the automatic control.

Without further elaboration, the foregoing Will so fully illustrate my invention that others may, by applying current knowledge, readily adapt the same for use under various conditions of service.

I claim:

In a radio receiver circuit, a volume control comprising a panel having an opening, a support having a threaded shank extending through said opening and having a bore, means acting on said shank and said pane1 for xedly securing the support to the panel, said support having spaced bars, a rack member slidably guided by said bars and having a resistor secured thereto to be carried thereby but insulated therefrom, a pinion meshing with said rack member, a rotative shaft xed to said pinion and extending through said bore and journaled in said bars, a second shaft axially slidably supported by said support, a circuit wire connected to said support with the latter electrically connected with said second shaft, a second wire connected with one end of said resistor, a Wiper contact carried by said second shaft and engaging said resistor, a rotary cam engaging said second shaft for moving the latter to shift said wiper contact along said resistor, and a spring supported at one end on said support and having its other end connected with said second shaft for yieldingly urging the latter into engagement With said rotary cam.

CURTIS O. NELSON. 

